On the Prediction of Machining-Induced Distortion in Forged Aerospace Components

Residual stresses introduced during the primary processing of aerospace components can lead to distortion during down-stream machining operations. Such distortion can be problematic from a manufacturing perspective in achieving the stringent dimensional tolerances required within the aerospace industry. Efforts to predict the resulting distortion during roughing and semi-finishing machining operations are therefore necessary to develop mitigation strategies to minimise part distortion and maximise right-first-time components.

In this study, the suitability of the finite element code DEFORM^TM-2D/3D for predicting the machining distortion in residually stressed components was assessed. A residual stress model for a condition of supply forging was validated through the hole drilling method. Machining distortion simulations were performed for the roughing and semi-finishing operations on front cover plate components with predicted distortions compared against probing data collected during experimental machining trials. The general trend of distortion as predicted by the finite element code is comparable with the experimental data, although the magnitudes of the distortions are inconsistent. Two strategies were investigated in order to compare the predicted distortions with the experimental data, and a preliminary sensitivity analysis was undertaken to identify the key variables that influence the predicted distortion.